Optimized Design and Multiphysics Analysis of a Ka-band Stacked Antenna for CubeSat Applications

Nowadays, the use of CubeSats for telecommunications and interplanetary missions is ever-increasing, thanks to their appealing low-cost character, as well as the space environment, which poses challenging multiphysics constraints on the antenna design. In this framework, the use of Ka-band for communication is explored. We present the design of a stacked patch antenna working across the down- and uplink Ka-bands. Materials and geometry of the radiator have been selected by accounting for the trade-off between electromagnetic, thermal and mechanical requirements. The design of the antenna is performed with a particle swarm optimization algorithm developed to control the bandwidth and matching. A bandwidth of [email protected] GHz has been obtained, with a gain around 8 dB. Furthermore, a multiphysics thermal analysis is performed to verify the operational stability of the optimized array, mounted on a 1 U satellite, in a case-study mission. The temperature patterns in the array are evaluated during the orbital period, and the influence of the operative temperature on the antenna responses and gain was considered. We found that the thermal loads can affect the antenna matching. However, thanks to the optimized design, the proposed stacked antenna can operate from −100 ∘ C to 100 ∘ C, with an almost constant gain. Finally, following a damage-tolerant approach, the level of mechanical deformation, which could be induced on the communication system, was studied. The stress analysis reveals that the stacked geometry can be used in a space mission. From the investigation of the strain and displacement field, we found a negligible impact on the antenna performance

Secondary mechanisms of anti-HER2 resistance in breast cancer: NF1 as an actionable target

n/

Effects of Carasau Dough Composition on the Microwave Dielectric Spectra up to 20 GHz

Carasau bread is a traditional product from Sardinia (IT). This flat bread is experiencing industrial advancement, through automation, and has great market potential. However, there is lack of understanding of how the composition (water content, salt and yeast concentration) affects the product quality. In this work, a microwave dielectric spectroscopy study is performed to investigate how the composition of Carasau bread doughs influences the spectra of this food product up to 20 GHz. A third-order Cole-Cole model was used for the physical and quantitative understanding of the electromagnetic properties of this food product. Then, we it has been studied how salt, yeast, and water variations affected the model parameters. This work could pave the route to the development of non-destructive, contactless microwave sensors for Carasau bread quality assessment

Josephson physics of spin-orbit-coupled elongated Bose-Einstein condensates

We consider an ultracold bosonic binary mixture confined in a quasi-one-dimensional double-well trap. The two bosonic components are assumed to be two hyperfine internal states of the same atom. We suppose that these two components are spin-orbit coupled to each other. We employ the two-mode approximation starting from two coupled Gross-Pitaevskii equations and derive a system of ordinary differential equations governing the temporal evolution of the interwell population imbalance of each component and of the polarization, which is the imbalance of the total populations of the two species. From this set of equations we disentangle the different macroscopic quantum tunneling and self-trapping scenarios occurring for both population imbalances and the polarization in terms of the interplay between the interatomic interactions and the other relevant energies in the problem, like the spin-orbit coupling or the conventional tunneling term. We find a rich dynamics in all three variables and discuss the experimental feasibility of such a system

A Coaxial Line Fixture Based on a Hybrid PSO-NLR Model for in Situ Dielectric Permittivity Determination of Carasau Bread Dough

Food quality is crucial in today's processing industry. The organoleptic properties of most food materials are known to depend on their water content. The monitoring of food quality and moisture content calls for engineering solutions. To this aim, given their nondestructive nature and cost-effective features, microwave sensors are a valuable tool. However, for some peculiar food processing industries, suitable engineered microwave devices must be designed. Therein, we will focus on the case of the Carasau bread industry. Carasau bread is a typical food product from Sardinia (IT). In this work, we will present the design, realization, and characterization of a coaxial fixture, working between 0.5 and 3 GHz, for the determination of the complex dielectric permittivity of Carasau bread dough. Through a nonlinear regression model based on a particle swarm optimization routine, the scattering parameters are used to retrieve the electromagnetic properties of bread doughs. By making a comparison with the complex dielectric permittivity measured with an open-ended coaxial probe, an average error of 3% for the real part and 6% for the imaginary part has been found. The proposed device is driven by a Raspberry Pi that controls the acquisition of a pocket-vector network analyzer (VNA), thus representing a cost-effective electronic system for industrial applications

Design of a Low-Profile Dual Linearly Polarized Antenna Array for mm-Wave 5G

This work proposes a dual linearly polarized antenna array for 5G mm-wave band, which is designed to be compatible with planar printed circuit board technology. The proposed antenna is engineered with a focus on simplifying the antenna geometry and eliminating any critical issues that may arise in antenna manufacturing. The proposed antenna has been evaluated, finding a 7% impedance bandwidth centered around 27.28 GHz. Additionally, the beam steering capability of the antenna is found to cover a ±30% angular width for both linear polarizations. These findings highlight the potential of the proposed antenna for use in 5G mm-wave band applications, where compatibility with planar printed circuit board technology and simplified antenna geometry are essential design requirements

A Low-profile Shared Aperture Antenna for FR1 and FR2 5G Frequency Bands

Shared-aperture antennas are attracting a wide interest in last of years, due to their inherent compactness and low-profile layout. More specifically, in this work a shared-aperture antenna for FR1 and FR2 frequency bands is proposed. The difference in size between the radiating elements operating the two frequency bands can be exploited to embed different antennas in the same area. A 4×4 patch array for FR2 is embedded inside a FR1 shaped patch antenna. The antenna system is designed by preserving a low-profile architecture suitable for planar technology. The performance of the antenna system are evaluated for both the bands achieving a 10-dB bandwidth equal to 0.14 GHz (3.8 %) for FR1 and to 2.32 GHz (8.6 %) for FR2. In FR2, a ±30° steering capability along the H plane is shown

Analysis of a Flexible Dual-Channel Octagonal Coil System for UHF MRI

Nowadays, MRI is focused on using ultra-high static magnetic fields (> 7 T) to increase the signal-to-noise ratio. The use of high fields, on the other hand, requires novel technical solutions as well as more stringent design criteria for specific absorption rate levels, reducing radiative effect and coil resistance. In this paper, two flexible RF coils for 7 T human magnetic resonance, and 298 MHz ultra-high frequency operations were analyzed and characterized. Imaging of lower human limbs is regarded as a case study. The lumped element theory and subsequent numerical simulations were used to fine-tune the single-coil element and the dual-coil array design, respectively. Here, we demonstrate how the shape, size, configuration, and presence of the sample influence the coil performance. The penetration depth of the B 1 -field and the specific absorption rate values have been determined numerically using two numerical surface phantoms: saline and a multilayer human tissue. A preliminary study in the presence of a saline solution phantom has been carried out to develop and validate the dual-coil system. The frequency response of the dual-coil array was measured to assess its robustness when coupled to twelve human volunteers. We found that our design is robust to variations in the anatomical properties of the human thighs, and hence to coil bending. The presented approach can be useful for the implementation of flexible devices with high sensitivity levels and low specific absorption rat

An in-line coaxial-to-waveguide transition for q-band single-feed-per-beam antenna systems

An in-line transition between a coaxial cable and rectangular waveguide operating in Q-band (33–50 GHz) is presented. The aim of the work is to minimize the modifications in the waveguide to the strictly necessary to overcome the manufacturing issues due to the high frequencies involved. In addition, the transition is compact and it does not increase the space occupation on the transverse section, this suggests its application in horn antennas clusters arrangement. The operating principle consists of both a modal conversion and an impedance matching between the devices. The modal conversion is realized in an intermediate region, where the coaxial penetrates in the waveguide: the device geometry is designed so that the electric field in the transition is a trade-off between the TEM mode of the coaxial and the TE10 of the guide. A shaped waveguide backshort and a reactive air gap in the coaxial cable co-participate to achieve the matching. An optimized Chebyshev stepped transformer completes the transition to fulfil the impedance mismatch with the full waveguide. The design issues and technological aspects are considered. The influences of the feeding pin misalignment, the presence of groove is included in the analysis and these practical aspects are discussed and numerically validated via the scattering parameters analysis of the proposed design. The return loss is higher than 25 dB over the whole Q-band

WSN Hardware for Automotive Applications: Preliminary Results for the Case of Public Transportation

The ubiquitous nature and great potential ofWireless Sensors Network has not yet been fully exploited in automotive applications. This work deals with the choice of the cost-effective hardware required to face the challenges and issues proposed by the new trend in the development of intelligent transportation systems. With this aim, a preliminary WSN architecture is proposed. Several commercially available open-source platforms are compared and the Raspberry Pi stood out as a suitable and viable solution. The sensing layer is designed with two goals. Firstly, accelerometric, temperature and relative humidity sensors were integrated on a dedicated PCB to test if mechanical or environmental stresses during bus rides could be harmful to the device. The monitored physical quantities could be used to improve the quality of service. Then, the rationale and functioning of the management and service layer is presented. The proposed cost-effective WSN node is employed and tested to transmit messages and videos